One video showed a 51-year-old Jewish man being beaten to the ground by three young men, who seemed to select him at random. Another showed an Orthodox Jewish man being chased across the street by a man wielding a tree branch. A third showed an Orthodox Jewish man hanging on to a fence as an assailant jumped and choked him.

The three incidents, all of which took place in Crown Heights, Brooklyn, in the past year, have raised alarms in the neighborhood and in the city’s large Orthodox Jewish community as a whole. Hate crimes are up citywide, but in Crown Heights, they have taken a particularly violent turn.

There were 55 hate crimes reported in New York City this year as of Feb. 17, an increase of 72 percent over the same period last year, the police said. Anti-Semitic crimes made up almost two-thirds of that, for a total of 36 crimes reported so far this year, compared with 21 last year.

The steep rise comes after a year when hate crimes were already increasing. Anti-Semitic crimes in 2018 were up 22 percent compared with 2017.

The wave of anti-Semitic attacks in Brooklyn continued on Saturday, when two men threw an object into the large front window of a Chabad Synagogue in Bushwick, Brooklyn, at about 2 a.m. No one was injured. The attack, which shattered the window, is being investigated as a possible bias crime, police said.

“Despite the intentions of this attack to divide and intimidate, our doors will remain as open as ever, welcoming visitors to join our growing Bushwick family,” Rabbi Menachem Heller wrote on Facebook shortly after the attack.

On Sunday, Gov. Andrew M. Cuomo directed the hate crimes unit of the State Police to assist local police in their investigation of the Bushwick attack. “This act of hate is shocking and abhorrent, especially at a time of great division in this country,” he said in a statement.

Citywide, the spike appears largely linked to vandalism and other property crimes, city police officials said.

Since the start of the year, police have made a number of arrests on the Upper West Side and in Brooklyn for spray-painted swastikas and similar acts. One repeat offender may be making the hate-crime increase look particularly intense, the Police Department’s chief of detectives, Dermot Shea, has said.

“We’ve had one individual account for 10 to 15 separate incidents,” Chief Shea said at a Feb. 5 news conference.

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The police stood outside the Union Temple of Brooklyn after anti-Semitic graffiti was found in the stairwell of the synagogue in November 2018.CreditJohn Taggart for The New York Times

But in Crown Heights, the increase in hate crimes has been more shocking because it has been marked by violent, seemingly unprovoked attacks on men and women in Jewish garb, many of which have been caught on surveillance video, and then widely viewed online. In many cases, there is no robbery, only the random attack.

Since October, there have been 15 violent, anti-Semitic incidents directed against ultra-Orthodox Jews in the neighborhood, according to an Israeli organization that tracks anti-Semitic incidents. Devorah Halberstam, the community liaison to the 71st Precinct, which covers Crown Heights, said she believes there have been even more than that.

“We need to go back to the drawing board. We cannot allow it to continue,” Ms. Halberstam said. “Walking down street and getting punched in the stomach? This is insanity.”

In January alone, several Orthodox Jews were punched, seemingly unprovoked, in broad daylight on Kingston Avenue, the main Jewish thoroughfare in Crown Heights. In late January, a 22-year-old Yeshiva student was beaten on the street while calling his parents on the phone in Australia. A few hours later, a 51-year-old man was beaten so badly by the same assailants that he was hospitalized.

The police have made arrests in many of these attacks, much to the relief of residents. Still, they wonder what is provoking this wave of violence.

Rabbi Eli Cohen, the executive director of the Crown Heights Jewish Community Council, has begun visiting nearby public schools with Geoffrey Davis, an African-American community leader, to try to understand what may be driving the attacks, as many of the assailants arrested by the police have been young men of color.

Mr. Davis, the Democratic district leader for the 43rd Assembly District, said that one need not look far to realize what can happen when tensions in the community between black residents and Jews go unaddressed.

He recalled the Crown Heights riots of 1991, when the neighborhood was thrown into turmoil for three days after a car escorting the Lubavitcher rebbe, the leader of the Chabad Jewish movement, struck two small children of Guyanese immigrants, killing one. During the rioting, a Jewish student was stabbed to death by a black assailant.

“It’s an emergency,” said Mr. Davis, who is sponsoring a listening tour through his Stop the Violence Foundation. “We have to address it now, before it reaches the next level.”

The neighborhood has worked over the decades to strengthen ties between its mainly Caribbean and Jewish populations through joint charity work and education programs run by the Jewish Children’s Museum and many other institutions. Crown Heights is the global headquarters of Chabad, an ultra-Orthodox movement, and thousands of its affiliated families live there.

Mr. Davis said that eighth graders in Prospect Lefferts Gardens suggested more multicultural after-school programs, new children’s books showing the two communities interacting and activities like chess tournaments to reduce tension between black and Jewish teens.

Rabbi Cohen said that Orthodox Jews in Crown Heights have largely gone about living their lives during this latest spike in crime. “There is concern when you open your computer and see another incident, but I don’t think it’s at a point where people feel that they are not safe on the streets,” he said.

A version of this article appears in print on , on Page A18 of the New York edition with the headline: An Uptick in Hate Crimes Against Jews. Order Reprints | Today’s Paper | Subscribe